SILICONE-ACRYLIC COPOLYMER

Description

FIELD OF THE INVENTION

[0001] The invention relates to silicone-acrylic copolymers and compositions comprising the copolymers and end use applications thereof.

BACKGROUND OF THE INVENTION

[0002] Acrylic-based polymers have been broadly used as adhesives, coatings and sealants since they are relatively low in cost, adhere well to a variety of different surfaces and, if necessary, can be formulated to build adhesion to a surface. The disadvantages of acrylic-based polymers include poor high temperature performance, poor low temperature performance, inability to adhere to substrates with low surface energies and the potential to build excessive adhesion to substrates with high surfaces energies.

[0003] Silicone-based polymers exhibit both good high and low temperature performance as adhesives, coatings and sealants. Silicone-based polymers have excellent chemical inertness, electrical insulating properties, biocompatibility, and the ability to adhere to low surface energy substrates. A primary disadvantage of silicone-based polymers is their high cost compared to other types of technologies. Other limitations include lower tack and limited adhesion build, when necessary, in comparison to acrylic-based polymers.

[0004] While individual silicone adhesive and acrylic polymer have distinct advantages, and although they may be physically blended to form a hybrid polymer system, the blend is thermodynamically unstable and ultimately leads to macroscopic phase separation and change in the blend properties over time.

[0005] An attempt to overcome this incompatibility has been addressed in WO 2007/145996, which forms an acrylic grafted silicone adhesive by a complex process. However, this complex process makes removal of residual monomer difficult and the level of crosslinking cannot be well controlled. If any unreacted silicone and acrylic components remain, this unreacted components lead to phase separation over time, even if the rest of components are covalently grafted.

[0006] US,A,3 650 813 does not disclose a scrambling catalyst having a defined pKa.

[0007] Covalent grafting of silicone and acrylics may be formed by reacting a silicone polymer and an acrylic polymer, however, a silicone resin is necessary form a hybrid polymer system. The resultant hybrid polymer system forms silicone resin as the center domain and silicone polymer and acrylics are attached to that domain. Hence, the resultant hybrid polymer system requires the silicone resin as the center domain to form a lattice-type polymer.

[0008] There is a need in the art for adhesives, coatings and sealants that exhibit the advantages of both acrylic- and silicone-based technologies without the disadvantages inherent in the prior art. This invention addresses this need.

SUMMARY OF THE INVENTION

[0009] The present invention is described as a silicone-acrylic copolymer which comprises a reaction product of a silicone polymer, a mixture of acrylic monomers wherein at least one acrylic monomer comprises a silane (meth)acrylic monomer and/or a siloxane (meth)acrylic macromer, a radical initiator; and a scrambling catalyst, wherein the ratio of the silicone polymer and the acrylic monomer is from 50:1 to 1:50; and wherein the scrambling catalyst is a catalyst which has a pKa value equal to or less than -6 or equal to or greater than 15.

[0010] Another invention is a silicone-acrylic copolymer comprises a reaction product of a silicone polymer, an acrylic polymer which comprises a silane or a siloxane functional group, and a scrambling catalyst, wherein the ratio of the silicone polymer and the acrylic polymer is from 50:1 to 50; and wherein the scrambling agent catalyst which has a pKa value equal or less than -6 or equal to or greather than 15.

[0011] A method of preparing a silicone-acrylic copolymer is defined in claim 13.

[0012] Yet another embodiment is directed to a composition comprising the silicone-acrylic copolymer as defined in claims 9 to 10.

[0013] Another embodiment is directed to an article comprising the silicone-acrylic copolymer as defined in claims 1 to 8. The article as defined in claim 12 may be formed into a solution adhesive, a water-born adhesive or a hot melt adhesive.

BRIEF DESCRIPTION OF THE FIGURES

[0014] 

Figure 1 is GPC chromatograms of silicone polymer (······), acrylic polymer (----) and silicone-acrylic copolymer (-).

Figure 2 is GPC chromatograms of the adhesives made from (1) silicone-acrylic copolymer with MQ resin (----) and (2) silicone polymer, acrylic polymer and MQ resin (-).

Figure 3 is a photograph of an adhesive made from silicone-acrylic copolymer with MQ resin (left, clear solution) and an adhesive made from silicone polymer, acrylic polymer and MQ resin (right, opaque solution).

DETAILED DESCRIPTION OF THE INVENTION

[0015] Percent by weight means, unless expressly stated otherwise, percent dry weight.

[0016] The invention provides a silicone-acrylic copolymer comprising a covalently bonded silicone polymer with an acrylic polymer through the -Si-O-Si- linkage, and the acrylic polymer contains at least one silane (meth)acrylic monomer and/or a siloxane (meth)acrylic macromer. copolymer comprising a covalently bonded silicone polymer with an acrylic polymer through the -Si-O-Si- linkage

[0017] The copolymer is prepared by reacting a mixture of a silicone polymer and mixtures of acrylic monomers that comprises at least one silane (meth)acrylic monomer and/or a siloxane (meth)acrylic macromer, with a radical initiator and a scrambling catalyst. The ratio of the silicone polymer to the acrylic monomer is from 50:1 to 1:50.

[0018] The copolymer is also prepared by reacting a mixture of a silicone polymer and an acrylic polymer that comprises at least one silane (meth)acrylic monomer and/or a siloxane (meth)acrylic macromer with a scrambling catalyst. The ratio of the silicone polymer to the acrylic monomer is also from 50:1 to 1:50.

[0019] Useful silicone polymers that can be used in the practice of the invention include silicone polymers that comprise an organosubstituted polysiloxane. Diorgano substituents include, for example, dimethyl, methylvinyl, methylphenyl, diphenyl, methylethyl, and 3,3,3-trifluoropropyl. In one embodiment, the diorgano substitutes are all dimethyl substituents. The silicone polymer will typically be end-capped with functional groups such as hydroxyl, alkoxyl, hydride, vinyl functional groups, and like groups. In one embodiment, end-capped functional groups are hydroxyl groups, alkoxy functional groups, hydride functional groups, vinyl functional groups or mixtures thereof. The molecular weight of polydiorganosiloxane will typically range from 100 to 2,000,000, preferably, from 20,000 to 150,000g/mol.

[0020] Acrylic monomers of the invention include at least one silane (meth)acrylic monomer and/or a siloxane (meth)acrylic macromer.

[0021] Examples of silane (meth)acrylic monomer include trialkoxylsilyl (meth)acrylates, and dialkoxysilyl (meth) acrylates. The silane (meth)acrylic monomer will typically be used in amounts of from 0.2 to 50 weight percent of the total weight of the acrylic polymer, more preferably the amount of silane (meth)acrylic monomer will range from 1.0 to 10 weight percent of the acrylic polymer.

[0022] Examples of siloxane (meth)acrylic macromer include polydimethylsiloxane mono (meth)acrylate, e.g. trialkoxylsilyl (meth)acrylates, dialkoxysilyl (meth)acrylates or methacrylates. Preferred siloxane (meth)acrylic macromers are trimethoxylsilyl and dimethoxymethylsilyl functional acrylates or methacrylates. An example of such monomer is methacryloxypropyl trimethoxylsilane. The siloxane (meth)acrylic macromer is in the content of 0.2 to 50 weight percent based on the total weight of acrylic monomers.

[0023] Other acrylic monomers are selected from a group of alkyl (meth)acrylate monomers. Preferred alkyl (meth)acrylates that may be used to practice the invention have up to 18 carbon atoms in the alkyl group, preferably from 1 to 12 carbon atoms in the alkyl group. These acrylic polymer components may comprise a low glass transition temperature (Tg) alkyl acrylate monomer. Low Tg monomers are those having a homopolymer Tg of less than 0°C. Preferred low Tg alkyl acrylates for use in the invention have from 4 to 10 carbon atoms in the alkyl group and include butyl acrylate, methyl acrylate, methyl methacrylate, t-octyl acrylamide, hydroxyethyl acrylate and acrylic acid, hydroxypropyl acrylate, hydroxylpropyl methacrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, decyl acrylate, isomers thereof, and combinations thereof. Particularly preferred are butyl acrylate, 2-ethylhexyl acrylate and isooctyl acrylate.

[0024] The low Tg acrylic monomers are preferably, but not necessarily, present in amounts greater than 40 wt % based upon the total monomer weight of the acrylic polymer. The acrylic polymer components may further comprise (meth)acrylate monomers having a high glass transition temperature. Examples include methyl acrylate, ethyl acrylate, methyl methacrylate and isobutyl methacrylate. It will be understood by a skilled practitioner that the choice of monomers is dictated by consideration of adhesive properties, compatibility with the other adhesive matrix components, drug solubility and so forth. Thus the monomer Tg is only one of many variables to be taken into account in any particular polymer design.

[0025] Useful acrylic monomers may be a nitrogen containing compound, in particular N-substituted acrylamides or methacrylamides. Examples include N-vinyl pyrrolidone, N-vinyl caprolactam, N-tertiary octyl acrylamide, dimethyl acrylamide, diacetone acrylamide, N-tertiary butyl acrylamide, N-isopropyl acrylamide, cyanoethylacrylate, N-vinyl acetamide and N-vinyl formamide.

[0026] Useful acrylic monomers may also be selected from a group of one or more hydroxyl containing functional monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate and/or hydroxypropyl methacrylate. Such hydroxy functional monomers are generally used in amounts up to 40 wt %, more typically from 0.5 to of 10 wt %, based on the total monomer weight of the acrylic polymer.

[0027] Useful acrylic monomers, if desired, may be selected from a group of carboxylic acid functional monomers. Useful carboxylic acids preferably contain from 3 to 6 carbon atoms and include, among others, acrylic acid, methacrylic acid, itaconic acid, and β-carboxyethyl acrylate. Acrylic acid is particularly preferred. Such carboxy functional monomers are generally used in amounts up to 25 wt %, more typically from 0.5 to of 10 wt %, based on the total monomer weight of the acrylic polymer.

[0028] Comonomers may be added to the acrylic monomers. Useful comonomers include vinyl acetate, styrene, alkyl di(meth)acrylates, glycidyl methacrylate and allyl glycidyl ether, as well as macromers such as, for example, poly(styryl)methacrylate.

[0029] Radical initiators are added with the acrylic monomers to form an acrylic prepolymer. While a particular polymerization method is described in the examples, the acrylic polymer component of the present invention may be prepared by conventional polymerization methods familiar to those of skill in the art. These methods include, without limitation solution polymerization, suspension polymerization, bulk polymerization and emulsion polymerization. In the practice of the invention, it may also be advantageous to reduce the residual monomer content, or remove or reduce solvent levels and/or other volatiles, following polymerization using methods that are known and conventional in the art. The adhesive may be applied from organic solution, aqueous dispersion, or from a melt.

[0030] Acrylic prepolymer may be formed as described above, or acrylic polymer may be used directly to form the silicone-acrylic copolymer. The acrylic polymer of the invention contains at least an alkoxysilyl functional monomer or/and polysiloxane-containing macromer. Examples of polysiloxane-containing macromers include polydimethylsiloxane mono acrylates or mono methacrylates.

[0031] The amount of polysiloxane-containing (meth)acrylic macromer will typically be used in amounts of from 0.2 to 50 weight percent, more preferably, 1 to 15 weight percent of the acrylic polymer.

[0032] Other acrylic polymer that can advantageously be used in the practice of the invention are acrylic polymers comprising end-capped alkoxysilyl functional groups or polysiloxane-blocked or -grafted copolymers. Examples of the end-capped alkoxysilyl functional groups are trialkoxylsilyl, dialkoxysilyl functional groups. Preferred end-capped alkoxysilyl functional groups are trimethoxylsilyl, dimethoxymethylsilyl, triethoxylsilyl and/or diethoxymethylsilyl functional groups. Examples of such polymers are MS-polymer (Kaneka). Block copolymers are also useful. An example of a polysiloxane block copolymer is polydimethylsiloxane-acrylic block copolymer. The preferred amount of siloxane block is 10 to 50 weight percent of the whole block polymer.

[0033] One acrylic polymer component that can be used in the practice of the invention is an acrylic polymer that comprises from 90 to 99.5 wt % of 2-ethylhexyl acrylate and from 0.5 to 10 wt % of dimethoxymethylsilyl methacrylate.

[0034] It has been discovered that polymers comprising greater than about 0.2 wt % of alkoxysilyl functional monomers are particularly well suited for use in adhesive compositions of the invention and can be used in the production of adhesive goods such as, for example, adhesive tapes and adhesive sheets by applying an adhesive or adhesive composition to a base material such as paper, cloth or plastic film.

[0035] The ratio of the silicone polymer and the acrylic monomer and/or polymer is from 50:1 to 1:50.

[0036] One preferable polymerization method is to form the silicone-acrylic copolymer by starting the polymerization of acrylic monomers in the presence of a radical initiator, a solvent and the silicone polymer. At the end of radical polymerization, a scrambling catalyst is introduced and the acrylic polymer reacts with the silicone polymer in the same reaction vessel to produce the copolymer. The alkoxysilyl functional monomers, once incorporated onto the acrylic polymer backbone, undergo condensation reactions with end-capped OH functional groups of the silicone polymer and fast re-equilibrated with a dynamic -Si-O-Si- bond cleavage and reformation in the presence of water/moisture and a strong acid or base catalyst. This step is called "a scrambling reaction," since it leads to completely miscible of the two intrinsically immiscible polymers: silicone polymer and acrylic polymer. The alkoxysilyl functional groups of the acrylic polymer undergo a self-crosslinking reaction in the presence of water/moisture and the catalyst from the scrambling reaction.

[0037] In another preferred polymerization method, the scrambling catalyst is introduced to the silicone polymer and acrylic polymer in the same reaction vessel to produce the copolymer. Again, the scrambling reaction takes place and results in the copolymer.

[0038] The useful scrambling catalysts have a pKa value less than or equal to -6 or greater than or equal to 15.

[0039] Examples of the scrambling catalyst are KOH, NaOH, LiOH, organolithium reagents, Grignard reagents, methanesulfonic acid, sulfuric acid, acidic clay, acidic ion exchange resins, and mixtures thereof. Other examples of the catalyst include organometallic salts of metals such as tin, titanium, aluminum, bismuth. Combination of more than one type of catalysts above can also be used.

[0040] Scrambling reaction may take place at room temperature, one preferred method is to conduct either reaction with heating at 50-160°C. The preferable temperature for the scrambling step is between 100-150°C. Scrambling reaction is preferably allowed to proceed at least until the rate of evolution of condensation byproducts, such as water, alcohol, and carbodioxide, is substantially removed. Heating is continued until the desired physical properties such as viscosity, clarity of the solution, and adhesion values are obtained. Typically the mixture of each step will be allowed to react from about 1 to about 24 hours.

[0041] The preferably solvent or a co-solvent is selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ether, tetrahydrofuran, ethyl acetate, methyl ethyl ketone, water and mixtures thereof.

[0042] Another embodiment is directed to a composition comprising the silicone-acrylic copolymer. The silicone-acrylic copolymer may be formulated into a variety of adhesives including a solution adhesive, emulsion adhesive and hot melt adhesive. Additional components may be added to the silicone-acrylic copolymer to form desired properties.

[0043] The silicone-acrylic copolymer may be blended with additional components to form a composition such as an adhesive, coating, sealant, and the like. Additional components may be blended with the copolymer of the invention to further increase or decrease desired property of the composition. Such components include silicone resin, tackifying agents, solubilizing agents, additives, antioxidants, polyester, polyether, polyurethane, natural rubber, synthetic rubber, viscosity modifying agents, fillers, and the like.

[0044] Useful silicone resin components that can be used in the practice of the invention include silicone resins that contain 0.05 to 5 weight percent of silicone-bound hydroxyl group and comprise triorganosiloxy units of R₃SiO_1/2 and tetrafunctional siloxyl units of SiO_4/2 in a mole ratio of from 0.5-1.5 R₃SiO_1/2 units for each SiO_4/2. The silicone resin may be blended with the silicone-acrylic copolymer, in a solid form or in a solution with toluene, xylene or heptane, and the like. Preferred organic R groups of the silicone resin are methyl, hydroxyl, vinyl, phenyl, (meth)acryloxy, and mixtures thereof. One preferred R group is a methyl group. The resins can be also further treated with Me₃SiOSiMe₃, ViMe₂SiOSiMe₂Vi, MeViPhSiOSiPhViMe, Me₃SiNHSiMe₃ or triorganosilane such as Me₃SiCl, Me₂ViSiCl or MeViPhSiCl to reduce the amount of OH in the silicone resin.

[0045] The addition of a silicone resin to the copolymer of the invention results in a different composition than adding silicon resin to silicone polymer and acrylic polymer that have not formed into a copolymer. While not bound to any theory, in the latter composition, the silicone resin forms the center domain which bridges the silicone polymer and acrylic polymer. These compositions are thermodynamically unstable and will ultimately lead to microscopic, or even macroscopic, phase separation over time. For composition made with the copolymer, the reactive sites on the silicone polymer has already reacted with acrylic monomers/polymers, and hence, the silicone resin does not form the center domains or bridge domains to connect the acrylic polymer and silicone polymer in the hybrid adhesive of the invention.

[0046] The addition of silicone resin to the silicone-acrylic copolymer is considered as a "bodying reacting" and is conducted in the presence of a bodying catalyst. Examples of the bodying catalyst for this bodying reaction is (NH₄)₂CO₃(S), ammonium carbamate, NH₄OH(aq), methanesulfonic acid, sulfuric acid, acidic clay, acidic Amberlyst™ ion exchange resins (Rohm and Haas), KOH, NaOH, LiOH, n-BuLi, and mixtures thereof. While the bodying reactions may take place at room temperature, one preferred method is to conduct the reaction with heating at 50-160°C. The preferable temperature of the bodying step is between 40-150°C.

[0047] The bodying reaction is preferably allowed to proceed at least until the rate of evolution of condensation byproducts, such as water, alcohol, and carbodioxide, is substantially removed. Heating can be continued until the desired physical properties such as viscosity, clarity of the solution, and adhesion values are obtained. Typically the mixture of each step will be allowed to react from 1 to 24 hours. When the bodying step of reaction is complete, the solids content of the resulting composition can be adjusted by adding or removing solvent.

[0048] Suitable tackifying agents are those known in the art including: (1) aliphatic hydrocarbons; (2) mixed aliphatic and aromatic hydrocarbons; (3) aromatic hydrocarbons; (4) substituted aromatic hydrocarbons; (5) hydrogenated esters; (6) polyterpenes; (7) mineral oils; and (8) wood resins or rosins and hydrogenated forms thereof. Useful levels of tackifiers are generally from 1 wt % to 30 wt % based on the weight of the total composition.

[0049] The copolymers of the invention may also be blended with additional polymers to enhance desired properties. Examples of polymers useful for blending include other acrylates, polysiloxanes, polyisobutylene, polyester, PPO, polyisoprene, polybutadiene, and styrenic block polymers. Examples of styrenic block copolymers include styrene-isoprene-styrene block copolymer (SIS), styrenebutadiene-styrene copolymer (SBS), styrene-ethylenebutene-styrene copolymers (SEBS), and diblock analogs thereof.

[0050] The compositions of the invention may include other additives known to those skilled in the art. These additives may include, pigments, fillers, fluorescent additives, flow and leveling additives, wetting agents, surfactants, antifoaming agents, rheology modifiers, permeation enhancers, stabilizers, and antioxidants.

[0051] Antioxidants may be added singly or in combination to protect the components against degradation during preparation and use of the adhesive compositions, and to ensure long-term thermal stability. In general up to 1 % by weight of one or more antioxidants may be included in the adhesive compositions, usually, from 0.1% to 0.5 % by weight.

[0052] Additional polymers may be further blended with the silicone-acrylic copolymers. Examples of such polymer include polyester, polyether, polyurethane, natural rubber. and synthetic rubber.

EXAMPLES

Example 1

[0053] An initial charge containing 20.0 g of butyl acrylate, 5.0 g of methyl methacrylate, 0.5 g of trimethoxysilylpropylacrylate, 40..8 g of silicone polymer (Wacker Elastomer 80N), 0.05 g of Vazo-67(2,2'-azodi(2-methylbutyronitrile)), and 50.0 g of xylene was mixed and charged to a 500-mL 4-neck round bottom flask equipped with stainless steel stirrer, thermometer, condenser, water bath, and slow addition funnels. The initial charge was heated to reflux while stirring. After 15 minutes of reflux, 30g of xylene and 0.3 g of Vazo-67 was added over a period of 2 hours. At the end of the addition, 0.1g of KOH (1.0 N in water) was added and the mixture was stirred at reflux for 4 hour. At the end of the hold period, the contents were cooled to room temperature and the polymer solution was discharged. Xylene was removed by rotorary evaporation under vacuum and heptane was added to reach a solid content of 50%.

Example 2

[0054] An initial charge containing 98.0 g of 2-EHA, 2.0 g of trimethoxysilylpropylacrylate, 400.0 g of silicone polymer (Wacker Elastomer 80N), 0.07 g of vazo-67, and 650.0 g of heptane was mixed and charged to a 2-L 4-neck round bottom flask equipped with stainless steel stirrer, thermometer, condenser, water bath, and slow addition funnels. The initial charge was heated to reflux while stirring. After 15 minutes of reflux, 50g of heptane and 0.5 g of Vazo -67 were added over a period of 2 hours. At the end of the addition, 0.2 g of KOH (1.0 N in water) was added and the mixture was stirred at reflux for 4 hour. At the end of the hold period, the content was cooled to room temperature and the polymer solution was discharged. Part of the heptane was removed by rotorary evaporation under vacuum, adjusting the solids content to 50%.

Example 3

[0055] An initial charge containing 20.0 g of 2-EHA, 5.0 g of methyl acrylate, 0.5 g of trimethoxysilylpropylacrylate, 0.05 g of vazo-67, and 50.0 g of xylene was mixed and charged to a 500-mL 4-neck round bottom flask equipped with stainless steel stirrer, thermometer, condenser, water bath, and slow addition funnels. The initial charge was heated to reflux while stirring. After 15 minutes of reflux, 30g of xylene and 0.3 g of Vazo -67 was added over a period of 2 hours. At the end of the addition, 0.1g of KOH (IN in water), and 40..8 g of silicone polymer (Wacker Elastomer 80N) were added and the mixture was stirred at reflux for 4 hour. At the end of the hold period, the contents were cooled to room temperature and the polymer solution was discharged. Xylene was removed by rotorary evaporation under vacuum and heptane was added, adjusting the solids content to 50%.

Example 4

[0056] An initial charge containing 98.0 g of 2-EHA, 2.0 g of trimethoxysilylpropylacrylate, 0.07 g of vazo-67, and 1.0 L of heptane were mixed and charged to a 2-L 4-neck round bottom flask equipped with stainless steel stirrer, thermometer, condenser, water bath, and slow addition funnels. The initial charge was heated to reflux while stirring. After 15 minutes of reflux, 50g of heptane and 0.5 g of Vazo -67 were added over a period of 2 hours. At the end of the addition, 0.2 g of KOH (1.0 N in water) and 400.0 g of silicone polymer (Wacker Elastomer 80N) were added and the mixture was stirred at reflux for 4 hour. At the end of the hold period, the content was cooled to room temperature and the polymer solution was discharged. Some heptane was removed by rotorary evaporation under vacuum, adjusting the solids content to 50%.

Example 5

[0057] An initial charge containing 98.0 g of 2-EHA, 2.0 g of trimethoxysilylpropylacrylate, 0.07 g of Vazo-67, and 80.0 g of heptane were mixed and charged to a 500-mL 4-neck round bottom flask equipped with stainless steel stirrer, thermometer, condenser, water bath, and slow addition funnels. The initial charge was heated to reflux while stirring. After 15 minutes of reflux, 20g of heptane and 0.5 g of Vazo -67 were added over a period of 2 hours. At the end of the addition, the flask content was held at reflux for 2 hour. At the end of the hold period, the content was cooled to room temperature and the polymer solution was discharged. The heptane was added, adjusting the solids content to 50%.

Example 6

[0058] A mixture of silicone-acrylic copolymer from Example 2 (50 g), methyl MQ resin (20 g), catalyst (NH₄)₂CO₃ (0.5 g), and heptane (30 g) was stirred at 60°C for 2 hr. The reaction mixture was then heated to reflux of heptane for 2 hr under a slow flow of nitrogen gas. Hexamethyldisilizane (2.0 g) was added and the reaction continued at reflux for 2 hr. The product was cooled to room temperature and packed in a glass jar.

Example 7

[0059] A mixture of silicone-acrylic copolymer from Example 2 (50 g), methyl MQ resin (20 g), catalyst NH₄OH(aq) (30% NH3, 0.2 g), and heptane (30 g) was stirred at reflux for 3 hr under a slow flow of nitrogen gas. Hexamethyldisilizane (2.0 g) was added and the reaction continued at reflux for 2 hr. The product was cooled to room temperature and packed in a glass jar.

Example 8

[0060] A mixture of silicone-acrylic copolymer from Example 1 (50 g), methyl MQ resin (20 g), catalyst KOH(aq) (0.1 g), and heptane (200 g) was stirred at 100°C for 3 hr under a slow flow of nitrogen gas. Hexamethyldisilizane (2.0 g) was added and the reaction continued at reflux for 2 hr. The product was cooled to room temperature and packed in a glass jar.

Example 9

[0061] A mixture of silicone-acrylic copolymer from Example 3 (50 g), methyl MQ resin (20 g), catalyst KOH (0.1 g), and heptane (30 g) was stirred at 100°C for 3 hr under a slow flow of nitrogen gas. Hexamethyldisilizane (2.0 g) was added and the reaction continued at reflux for 2 hr. The product was cooled to room temperature and packed in a glass jar.

Example 10

[0062] A mixture of silicone-acrylic copolymer from Example 4 (50 g), methyl MQ resin (20 g), catalyst NH₄OH(aq) (30% NH3, 0.2 g), and heptane (30 g) was stirred at reflux for 3 hr under a slow flow of nitrogen gas. Hexamethyldisilizane (2.0 g) was added and the reaction continued at reflux for 2 hr. The product was cooled to room temperature and packed in a glass jar.

Example 11

[0063] A mixture of acrylic copolymer from Example 5 (50 g), silicone polymer (Wacker Elastomer 80N, 50 g), catalyst KOH(aq) (1.0 N in water) (0.2 g), and heptane (300 g) was stirred at reflux for 4 hr under a slow flow of nitrogen gas. And then methyl MQ resin (50 g) and KOH(aq) (1.0 N in water) (0.1 g) were added and the mixture was stirred at reflux for 2 hr. Acetic acid (0.03g) was added and the mixture was stirred at reflux for 0.5 hr. NH₄OH(aq) (30% NH3, 0.05 g) was added and the mixture was stirred at reflux for 0.5 hr. Hexamethyldisilizane (2.0 g) was added and the reaction continued at reflux for 1 hr. The heptane solvent was removed by rota-vap and the resulting hot melt adhesive was packed in a glass jar.

Example 12

[0064] A mixture of acrylic copolymer from Example 5 (50 g), silicone polymer (Wacker Elastomer 80N, 50 g), catalyst KOH(aq) (1.0 N in water) (0.2 g), and heptane (300 g) was stirred at reflux for 4 hr under a slow flow of nitrogen gas. Acetic acid (0.03g) was added and the mixture was stirred at reflux for 0.5 hr. The product was cooled to room temperature and packed in a glass jar.

Example 13: Comparative Example

[0065] A mixture of acrylic copolymer from Example 5 (50 g), silicone polymer (Wacker Elastomer 80N, 50 g), methyl MQ resin (50 g), catalyst KOH(aq) (1.0 N in water) (0.2 g), and heptane (300 g) was stirred at reflux for 4 hr under a slow flow of nitrogen gas. Acetic acid (0.03g) was added and the mixture was stirred at reflux for 0.5 hr. Hexamethyldisilizane (5.0 g) was added and the reaction continued at reflux for 1 hr. The product was cooled to room temperature and packed in a glass jar.

Example 14

[0066] A mixture of acrylic copolymer from Example 5 (50 g), silicone polymer (Wacker Elastomer 80N, 50 g), catalyst KOH(aq) (1.0 N in water) (0.2 g), and heptane (300 g) was stirred at reflux for 4 hr under a slow flow of nitrogen gas. Acetic acid (0.03g) was added and the mixture was stirred at reflux for 0.5 hr. NH₄OH(aq) (30% NH3, 0.2 g) and then methyl MQ resin (50 g) were added and the mixture was stirred at reflux for 3 hr. Hexamethyldisilizane (5.0 g) was added and the reaction continued at reflux for 1 hr. The product was cooled to room temperature and packed in a glass jar.

Example 15

[0067] A mixture of acrylic copolymer from Example 5 (50 g), silicone polymer (Wacker Elastomer 80N, 50 g), catalyst KOH(aq) (1.0 N in water) (0.2 g), and heptane (300 g) was stirred at reflux for 4 hr under a slow flow of nitrogen gas. (NH₄)₂CO₃ (0.5 g) and then methyl MQ resin (50 g) were added and the mixture was stirred at 60C for 3 hr and then reflux for 1 hr. Hexamethyldisilizane (5.0 g) was added and the reaction continued at reflux for 1 hr. The product was cooled to room temperature and packed in a glass jar.

Example 16

[0068] An initial charge containing 24.5 g of 2-EHA, 0.5 g of trimethoxysilylpropylacrylate, 50.0 g of silicone polymer (Wacker Elastomer 80N), 0.03 g of Vazo-67, and 250.0 g of heptane was mixed and charged to a 1-L 4-neck round bottom flask equipped with stainless steel stirrer, thermometer, condenser, water bath, and slow addition funnels. The initial charge was heated to reflux while stirring. After 15 minutes of reflux, 50g of heptane and 0.5 g of Vazo -67 were added over a period of 2 hours. At the end of the addition, 0.2 g of KOH(aq) (1.0 N in water) was added and the mixture was stirred at reflux for 4 hour. Acetic acid (0.03g) was added and the mixture was stirred at reflux for 0.5 hr. NH₄OH(aq) (30% NH3, 0.2 g) and then methyl MQ resin (50 g) were added and the mixture was stirred at reflux for 4 hr. Hexamethyldisilizane (5.0 g) was added and the reaction continued at reflux for 1 hr. The product was cooled to room temperature and packed in a glass jar.

Example 17

[0069] An initial charge containing 24.5 g of 2-EHA, 0.5 g of trimethoxysilylpropylacrylate, 50.0 g of silicone polymer (Wacker Elastomer 80N), 0.03 g of Vazo-67, and 250.0 g of heptane was mixed and charged to a 1-L 4-neck round bottom flask equipped with stainless steel stirrer, thermometer, condenser, water bath, and slow addition funnels. The initial charge was heated to reflux while stirring. After 15 minutes of reflux, 50g of heptane and 0.5 g of Vazo -67 were added over a period of 2 hours. At the end of the addition, 0.2 g of KOH(aq) (1.0 N in water) was added and the mixture was stirred at reflux for 4 hour. (NH₄)₂CO₃ (0.5 g), NaHCO₃ (0.1g) and methyl MQ resin (50 g) were added and the mixture was stirred at 60C for 3 hr and then reflux for 1 hr. Hexamethyldisilizane (5.0 g) was added and the reaction continued at reflux for 1 hr. The product was cooled to room temperature and packed in a glass jar.

Example 18

[0070] An initial charge containing 24.5 g of 2-EHA, 0.5 g of trimethoxysilylpropylacrylate, 0.03 g of Vazo-67, and 50.0 g of heptane was mixed and charged to a 1-L 4-neck round bottom flask equipped with stainless steel stirrer, thermometer, condenser, water bath, and slow addition funnels. The initial charge was heated to reflux while stirring. After 15 minutes of reflux, 50g of heptane and 0.5 g of Vazo -67 were added over a period of 2 hours. At the end of the addition, 50.0 g of silicone polymer (Wacker Elastomer 80N), 0.2 g of KOH(aq) (1.0 N in water) and 200 g of heptane were added and the mixture was stirred at reflux for 4 hour. Acetic acid (0.03g) was added and the mixture was stirred at reflux for 0.5 hr. NH₄OH(aq) (30% NH3, 0.2 g) and methyl MQ resin (50 g) were added and the mixture was stirred at reflux for 4 hr. Hexamethyldisilizane (5.0 g) was added and the reaction continued at reflux for 1 hr. The product was cooled to room temperature and packed in a glass jar.

Example 19

[0071] The GPC Chromatograms (Waters Alliance 2695 GPC) of silicone polymer (Wacker Elastomer 80N) (······), acrylic polymer (Example 5) (----), and the silicone-acrylic copolymer of Example 12 (-) are shown in Figure 1.

[0072] Figure 1 shows that the silicone-acrylic copolymer has higher molecular weight than the individual polymers, indicating the formation of a silicone-acrylic copolymer.

Example 20: GPC graph

[0073] The GPC chromatograms (Waters Alliance 2695 GPC) of the adhesives made from (1) silicone-acrylic copolymer with MQ resin, Example 14 (----) and (2) silicone polymer, acrylic polymer and MQ resin, Example 13 (-) are shown in Figure 2.

[0074] Figure 2 shows that the two adhesives have different GPC characteristics. The adhesive made from the silicone-acrylic copolymer (Example 14) has a broader and higher molecular weight distribution and peaks than the adhesive made from Example 13.

Example 21: Photograph

[0075] The above samples from Example 20 were photographed with a Sony Cyber-Shot DSC-S85, 4.0Mega Pixels.

[0076] . The silicone-acrylic hybrid adhesive of the invention (Example 14) is a clear solution in heptane (left). The adhesive of Example 13 is opaque solution in heptane. This adhesive is thermodynamically unstable and will ultimately lead to microscopic or even macroscopic phase separation over time.

Claims

1. A silicone-acrylic copolymer comprising a reaction product of:

(a) a silicone polymer;

(b) (i) a mixture of acrylic monomers and a radical initiator, wherein at least one acrylic monomer comprises a silane (meth)acrylic monomer and/or a siloxane (meth)acrylic macromer; or (ii) an acrylic polymer which comprises a silane or a siloxane functional group; and

(c) a scrambling catalyst;

wherein the ratio of (a) to (b) is from 50:1 to 1:50; and
wherein the scrambling catalyst is a catalyst which has a pKa value equal to or less than -6 or equal to or greater than 15.

2. The silicone-acrylic copolymer of claim 1 wherein the silicone polymer is an organodisubstituted polysiloxane which is end-capped with a hydroxyl functional group, alkoxy functional group, hydride functional group, vinyl functional group or mixtures thereof.

3. The silicone-acrylic copolymer of claim 1 or 2 wherein the silicone polymer has an average molecular weight of from 100 g/mol to 2,000,000 g/mol.

4. The silicone-acrylic copolymer of claims 1 to 3 wherein the silane (meth)acrylic monomer and/or the siloxane (meth)acrylic macromer is in the content of 0.2 to 50 wt % based on the total weight of acrylic monomers.

5. The silicone-acrylic copolymer of claim 4 wherein the silane (meth)acrylic monomer is selected from the group consisting of dialkoxysilyl (meth)acrylates, trialkoxylsilyl (meth)acrylates, and mixtures thereof.

6. The silicone-acrylic copolymer of claims 1 to 3 wherein the acrylic polymer further comprises an acrylic monomer which is selected from butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methyl acrylate, methyl methacrylate, t-octyl acrylamide, hydroxyethyl acrylate and acrylic acid, hydroxypropyl acrylate, hydroxylpropyl methacrylate or mixtures thereof.

7. The silicone-acrylic copolymer of claim 6 wherein the two terminal ends of the acrylic polymer is end-capped with an alkoxysilyl functional group which is selected from trimethoxylsilyl group, dimethoxymethylsilyl group, triethoxylsilyl group, diethoxymethylsilyl group or mixtures thereof.

8. The silicone-acrylic copolymers of claims 1 to 7 wherein the scrambling catalyst is selected from the group consisting KOH, NaOH, LiOH, organolithium reagents, Grignard reagents, methanesulfonic acid, sulfuric acid, acidic clay, acidic ion exchange resins, and mixtures thereof.

9. A composition comprising the silicone-acrylic copolymer of claims 1 to 8 further comprising a tackifier, silicone resin, solubilizing agents, polyester, polyether, polyurethane, natural rubber, synthetic rubber, antioxidant, viscosity modifying agent, filler or mixtures thereof.

10. The composition of claim 9 comprising the silicone resin, and the silicone resin contains at least one tetrafunctional siloxyl unit SiO_4/2 and at least one triorganosiloxy unit R₃SiO_1/2, wherein the R is methyl, hydroxyl, vinyl, phenyl, (meth)acryloxy or mixtures thereof, and the mole ratio of the units SiO_4/2 to R₃SiO_1/2 is from 1:2 to 2:1.

11. An article comprising the silicone-acrylic copolymer of claims 1 to 8.

12. The article of claim 11 which is a coating, sealant or adhesive.

13. A method of preparing a silicone-acrylic copolymer of claim 1 comprising combining the silicone polymer, the mixtures of acrylic monomers with the radical initiator or the acrylic polymer, the scrambling catalyst, a solvent and heating and refluxing at the solvent refluxing temperature.

Ansprüche

1. Silikon-Acryl-Copolymer, umfassend ein Umsetzungsprodukt aus:

(a) einem Silikonpolymer;

(b) (i) einer Mischung aus Acrylmonomeren und einem Radikalstarter, wobei mindestens ein Acrylmonomer ein Silan(meth)acrylmonomer und/oder ein Siloxan(meth)acrylmakromer umfasst; oder (ii) einem Acrylpolymer, das eine funktionelle Silan- oder eine funktionelle Siloxangruppe umfasst; und

(c) einen Scrambling-Katalysator;

wobei das Verhältnis von (a) zu (b) von 50:1 bis 1:50 beträgt; und
wobei der Scrambling-Katalysator ein Katalysator ist, der einen pKa-Wert aufweist, der gleich groß wie oder kleiner als -6 oder gleich groß wie oder größer als 15 ist.

2. Silikon-Acryl-Copolymer nach Anspruch 1, wobei das Silikonpolymer ein organodisubstituiertes Polysiloxan ist, das mit einer funktionellen Hydroxylgruppe, einer funktionellen Alkoxygruppe, einer funktionellen Hydridgruppe, einer funktionellen Vinylgruppe oder Mischungen daraus endgruppenverschlossen ist.

3. Silikon-Acryl-Copolymer nach Anspruch 1 oder 2, wobei das Silikonpolymer ein durchschnittliches Molekulargewicht von 100 g/mol bis 2.000.000 g/mol aufweist.

4. Silikon-Acryl-Copolymer nach Anspruch 1 bis 3, wobei das Silan(meth)acrylmonomer und/oder das Siloxan(meth)acrylmakromer in einem Gehalt von 0,2 bis 50 Gew.-% bezogen auf das Gesamtgewicht von Acrylmonomeren vorliegt.

5. Silikon-Acryl-Copolymer nach Anspruch 4, wobei das Silan(meth)acrylmonomer ausgewählt ist aus der Gruppe bestehend aus Dialkoxysilyl(meth)acrylaten, Trialkoxylsilyl(meth)acrylaten und Mischungen daraus.

6. Silikon-Acryl-Copolymer nach Anspruch 1 bis 3, wobei das Acrylpolymer ferner ein Acrylmonomer umfasst, das ausgewählt ist aus Butylacrylat, 2-Ethylhexylacrylat, Isooctylacrylat, Methylacrylat, Methylmethacrylat, t-Octylacrylamid, Hydroxyethylacrylat und Acrylsäure, Hydroxypropylacrylat, Hydroxylpropylmethacrylat oder Mischungen daraus.

7. Silikon-Acryl-Copolymer nach Anspruch 6, wobei die zwei terminalen Enden des Acrylpolymers mit einer funktionellen Alkoxysilylgruppe, die aus einer Trimethoxylsilylgruppe, Dimethoxymethylsilylgruppe, Triethoxylsilylgruppe, Diethoxymethylsilylgruppe oder Mischungen daraus ausgewählt ist, endgruppenverschlossen sind.

8. Silikon-Acryl-Copolymer nach Anspruch 1 bis 7, wobei der Scrambling-Katalysator ausgewählt ist aus der Gruppe bestehend aus KOH, NaOH, LiOH, Organolithiumreagenzien, Grignard-Reagenzien, Methansulfonsäure, Schwefelsäure, saurem Ton, sauren Ionenaustauschharzen und Mischungen daraus.

9. Zusammensetzung, umfassend das Silikon-Acryl-Copolymer nach Anspruch 1 bis 8, ferner umfassend einen Klebrigmacher, ein Silikonharz, Lösungsvermittler, einen Polyester, einen Polyether, ein Polyurethan, einen Naturkautschuk, einen Synthesekautschuk, ein Antioxidationsmittel, ein Viskosität modifizierendes Mittel, einen Füllstoff oder Mischungen daraus.

10. Zusammensetzung nach Anspruch 9, umfassend das Silikonharz, und wobei das Silikonharz mindestens eine tetrafunktionelle Siloxyleinheit SiO_4/2 und mindestens eine Triorganosiloxyeinheit R₃SiO_1/2 enthält, wobei das R Methyl, Hydroxyl, Vinyl, Phenyl, (Meth)acryloxy oder Mischungen daraus ist und das Molverhältnis der Einheiten SiO_4/2 zu R₃SiO_1/2 1:2 bis 2:1 beträgt.

11. Erzeugnis, umfassend das Silikon-Acryl-Copolymer nach Anspruch 1 bis 8.

12. Erzeugnis nach Anspruch 11, bei dem es sich um eine Beschichtung, ein Dichtungsmaterial oder einen Klebstoff handelt.

13. Verfahren zum Herstellen eines Silikon-Acryl-Copolymers nach Anspruch 1, umfassend ein Kombinieren des Silikonpolymers, der Mischungen von Acrylmonomeren mit dem Radikalstarter oder dem Acrylpolymer, dem Scrambling-Katalysator, einem Lösungsmittel, und Erwärmen und Zurückfließen bei der Lösungsmittelrückflusstemperatur.

Revendications

1. Copolymère silicone-acrylique comprenant un produit de réaction :

(a) d'un polymère de silicone ;

(b) (i) d'un mélange de monomères acryliques et d'un initiateur de radical, dans lequel au moins un monomère acrylique comprend un monomère silane (méth)acrylique et/ou un macromère siloxane (méth)acrylique ; ou (ii) d'un polymère acrylique qui comprend un groupe fonctionnel silane ou siloxane ; et

(c) d'un catalyseur de brouillage ;

dans lequel le rapport entre (a) et (b) est de 50:1 à 1:50 ; et
dans lequel le catalyseur de brouillage est un catalyseur qui a une valeur pKa inférieure ou égale à -6 ou supérieure ou égale à 15.

2. Copolymère silicone-acrylique selon la revendication 1 dans lequel le polymère de silicone est un polysiloxane organodisubstitué qui est à extrémité coiffée par un groupe fonctionnel hydroxyle, un groupe fonctionnel alcoxy, un groupe fonctionnel hydrure, un groupe fonctionnel vinyle ou leurs mélanges.

3. Copolymère silicone-acrylique selon la revendication 1 ou 2 dans lequel le polymère de silicone a un poids moléculaire moyen compris entre 100 g/mol et 2 000 000 g/mol.

4. Copolymère silicone-acrylique selon les revendications 1 à 3 dans lequel le monomère silane (méth)acrylique et/ou le macromère siloxane (méth)acrylique est/sont d'une teneur comprise entre 0,2 et 50 % en poids par rapport au poids total des monomères acryliques.

5. Copolymère silicone-acrylique selon la revendication 4 dans lequel le monomère silane (méth)acrylique est choisi dans le groupe constitué de (méth)acrylates de dialcoxysilyle, de (méth)acrylates de trialcoxylsilyle et de leurs mélanges.

6. Copolymère silicone-acrylique selon les revendications 1 à 3 dans lequel le polymère acrylique comprend en outre un monomère acrylique qui est choisi parmi l'acrylate de butyle, l'acrylate de 2-éthylhexyle, l'acrylate d'isooctyle, l'acrylate de méthyle, le méthacrylate de méthyle, l'acrylamide de t-octyle, l'acrylate d'hydroxyéthyle et l'acide acrylique, l'acrylate d'hydroxypropyle, le méthacrylate d'hydroxylpropyle ou leurs mélanges.

7. Copolymère silicone-acrylique selon la revendication 6 dans lequel les deux extrémités terminales du polymère acrylique sont à extrémité coiffée par un groupe fonctionnel alcoxysilyle qui est choisi parmi le groupe triméthoxylsilyle, le groupe diméthoxyméthylsilyle, le groupe triéthoxylsilyle, le groupe diéthoxyméthylsilyle ou leurs mélanges.

8. Copolymères silicone-acrylique selon les revendications 1 à 7 dans lesquels le catalyseur de brouillage est choisi dans le groupe constitué de KOH, de NaOH, de LiOH, de réactifs d'organolithium, de réactifs de Grignard, d'acide méthanesulfonique, d'acide sulfurique, d'argile acide, de résines échangeuses d'ions acides et de leurs mélanges.

9. Composition comprenant le copolymère silicone-acrylique selon les revendications 1 à 8 comprenant en outre un agent poisseux, une résine de silicone, des agents solubilisants, du polyester, du polyéther, du polyuréthane, du caoutchouc naturel, du caoutchouc synthétique, un antioxydant, un agent modifiant la viscosité, une charge ou des mélanges de ceux-ci.

10. Composition selon la revendication 9 comprenant la résine de silicone, et la résine de silicone contient au moins un motif siloxyle tétrafonctionnel SiO_4/2 et au moins une unité triorganosiloxy R₃SiO_1/2, dans laquelle le R est un méthyle, un hydroxyle, un vinyle, un phényle, un (méth)acryloxy ou des mélanges de ceux-ci, et le rapport molaire des unités SiO_4/2 à R₃SiO_1/2 est de 1:2 à 2:1.

11. Article comprenant le copolymère silicone-acrylique selon les revendications 1 à 8.

12. Article selon la revendication 11 qui est un revêtement, un colmatant ou un adhésif.

13. Procédé de préparation d'un copolymère silicone-acrylique selon la revendication 1 comprenant la combinaison du polymère de silicone, les mélanges de monomères acryliques avec l'initiateur de radical ou le polymère acrylique, le catalyseur de brouillage, un solvant et le chauffage et le reflux à la température de reflux du solvant.

Drawing